Why is the GPS100 Course Over Ground (COG) erratic at low speeds?

Estimated Reading Time: < 1 Minute

148 Mark Oslund June 22, 2008 GPS100(Discontinued) 0 3974

The GPS100 computes Course Over Ground (COG) by observing prior fixes or positions and extrapolating the direction of travel from those fixes. If the vessel is not moving, then the GPS100 can not extrapolate the direction of travel and the readings become nonsensical or erratic. This only happens below 0.75 knots or less.